add swconfig package

pkgs/default.nix

@@ -37,4 +37,5 @@
   # https://sourceforge.net/p/squashfs/mailman/message/26599379/
   lzma = callPackage ./lzma {};
 
+  swconfig = callPackage ./swconfig {};
 }

pkgs/swconfig/default.nix

@@ -0,0 +1,33 @@
+{ stdenv, buildPackages, libnl, ...} :
+let switchDotH = buildPackages.fetchurl {
+  url = "https://git.openwrt.org/?p=openwrt/openwrt.git;a=blob_plain;f=target/linux/generic/files/include/uapi/linux/switch.h;hb=99a188828713d6ff9c541590b08d4e63ef52f6d7";
+  sha256 = "15kmhhcpd84y4f45rf8zai98c61jyvkc37p90pcxirna01x33wi8";
+  name="switch.h";
+};
+in stdenv.mkDerivation {
+  src = buildPackages.fetchFromGitHub {
+    owner = "jekader";
+    repo = "swconfig";
+    rev = "66c760893ecdd1d603a7231fea9209daac57b610";
+    sha256 = "0hi2rj1a1fbvr5n1090q1zzigjyxmn643jzrwngw4ij0g82za3al";
+  };
+  name = "swconfig";
+  buildInputs = [ buildPackages.pkgconfig ];
+  nativeBuildInputs = [ libnl ];
+  CFLAGS="-O2 -Ifrom_kernel -I${libnl.dev}/include/libnl3";
+  LDFLAGS="-L${libnl.out}/lib";
+
+  patchPhase = ''
+    mkdir -p from_kernel/linux
+    cp ${switchDotH} from_kernel/linux/switch.h
+  '';
+
+  buildPhase = ''
+    make swconfig
+    $STRIP swconfig
+  '';
+  installPhase = ''
+    mkdir -p $out/bin
+    cp swconfig $out/bin
+  '';
+}